In a semiconductor device manufacturing process, it is required to perform a thermal processing process on a substrate at a uniform temperature. Examples of the manufacturing process may include chemical vapor deposition and silicon epitaxial growth processes in which a material layer having a gas phase is deposited on a semiconductor substrate placed on a susceptor within a reactor. The susceptor is generally heated at a temperature of about 400° C. to about 1,250° C. by resistance heating, high-frequency heating, infrared heating, and the like. In this state, a gas chemically reacts while passing through the reactor to cause the deposition in the state of the gas phase at a position that is very close to a surface of the substrate. Due to this reaction, a desired production may be deposited on the substrate.
A semiconductor device includes a plurality of layers on a silicon substrate. The layers are deposited on the substrate through the deposition process. The deposition process has several important issues. The issues are important in evaluating a deposited layer and selecting a deposition method.
First, one of the important issues may be quality of the deposited layer. This represents compositions, contamination levels, defect density, and mechanical and electrical properties of the deposited layer. The deposited layer may be changed in composition according to deposition conditions. This is very important for obtaining a specific composition.
Second, one of the important issues may be a uniform thickness crossing a wafer. Specifically, a layer deposited on a pattern having a nonplanar shape in which a stepped portion is formed is very important in thickness. Whether the deposited layer has a uniform thickness may be determined through a step coverage which is defined as a value obtained by dividing a minimum thickness of a layer deposited on the stepped portion by a thickness of a layer deposited on a top surface of a pattern.
The other issue with respect to the deposition may be a filling space. This includes gap filling in which an insulation layer including an oxide layer is filled between metal lines. The gap is provided for physically and electrically insulating the metal lines from each other. Among the above-described issues, the uniformity may be one of important issues related to the deposition process. A non-uniform layer may cause high electrical resistance on the metal lines to increase possibility of mechanical damage.